This is the first application filed for the present invention.
Not Applicable.
The present invention relates to an apparatus for magnetically treating fluids flowing through a conduit, and in particular, to an apparatus for inhibiting the deposition of barium sulfate scale on the inside of downhole oil production tubulars in a hydrocarbon well
Fouling deposits in oil and gas production tubing has always been a problem to some extent. As more marginal fields are brought into production, however, the problem is exacerbated. It is well known that asphaltines and paraffins in heavy crudes tend to foul production tubing and, if untreated, may completely block the tubing. In oil and gas wells that also produce water, mineral scaling may also occur. One of the most troublesome of mineral scales is barium sulphate, due to its very low solubility. Consequently, barium sulphate is becoming an increasing problem in the flow assurance management of hydrocarbon wells.
For some years, there has been an interest in using magnetic fields to treat flowing fluids, including fluids produced from hydrocarbon wells. The preferred means for generating magnetic fields in downhole environments are permanent magnets, since they have no power supply requirement.
The concept of using permanent magnets to treat fluid flow in oil wells to improve flow assurance is well known in the art. However, the arrangement of magnetic polarity orientation and structural improvements for work efficiency are still evolving.
As an example, U.S. Pat. No. 4,564,448 which issued Jan. 14, 1986 to O""Meara, Jr., entitled Device for Treating Fluids with Magnetic Lines of Force, discloses a tool for treating fluids which includes a core magnet assembly and at least one spaced-apart and concentric elongated ring magnet assembly forming at least one annular passageway for the fluid. Each magnet assembly includes at least one tier of at least two magnetic sections arranged in coaxial lines in Nxe2x80x94N and Sxe2x80x94S relation in at least one permanent magnet (FIG. 1). The magnet assemblies are positioned so that the polarities of adjacent polar ends of magnetic sections in one of the magnet assemblies are unlike the polarities of the oppositely disposed adjacent polar ends of magnetic sections in a spaced-apart magnet assembly. The device described in this prior patent has a series (tier) of magnets axially oriented in the core with an annular fluid passageway around it. However, the magnetic flux fields are established as narrow radial bands between the opposite poles of magnets in the core assembly and magnets of the ring assembly (FIG. 1). Therefore, the ring magnet assembly is essential to the operability of the device.
As another example, U.S. Pat. No. 5,024,271 which issued Jun. 18, 1991 to Bait Institute of Applied Design of New Materials, entitled Permanent-Magnet Wax-Proof Device. This patent discloses a permanent magnet wax-proof tool which includes one or more than one magnetic pole pairs, each of which includes two magnetic circuit units, each unit comprising radially oriented magnets co-operating with axially or circumferentially oriented magnets or both (FIGS. 3 to 6). The second embodiment of the invention described in this patent (FIGS. 5, 6, 8 and 10) can be connected in series with a sucker rod used in pumping some oil wells. This embodiment forms a magnet core and the fluids flow around the core. The device described in this patent, and in particular as the second embodiment has axially oriented magnets in the pairs of magnetic circuits which are incorporated in a sucker rod connector and form a magnetic core, treating the fluids flowing around the core. This patent emphasizes that the main purpose of adding the axially oriented side magnets or the circumferentially oriented strip magnets, or both, to the radially oriented tile magnets is to suppress the leakage of magnetic field generated by the radially oriented tile magnets so as to significantly concentrate and thus enhance the field strength in the main area of oil flow.
As a further example, U.S. Pat. No. 5,700,376 which issued on Dec. 23, 1997 to Carpenter, is entitled Method and Apparatus for Magnetically Treating Flowing Liquids. This patent discloses an apparatus which includes a plurality of parallel spacers secured at circumferentially spaced locations to the inside of a cylindrical portion of a housing, with a series of axially spaced, first and second magnets sandwiched between the inside surface of the cylindrical portion of the housing and the outer surface of a pipe and circumferentially spaced from each other and from the spacers. The poles of the first and second magnets are oppositely oriented, so that a flux field is formed between the poles of the spaced-apart magnets.
As yet another example, U.S. Pat. No. 5,178,757 which issued Jan. 12, 1993 to Mag-Well, Inc., is entitled Magnetic, Fluid-Conditioning Tools. This patent describes a device that includes an elongated hollow core, at least one fluid passage extending longitudinally through the core, at least two longitudinally extending arrays of magnets on an exterior surface of the core on opposite sides of the fluid passage. The magnets in each array are in register across the fluid passage, each registered pair of magnets having adjacent opposite poles to provide a magnetic field substantially perpendicular to the passage. An alternate embodiment of the device has three longitudinally extending arrays of magnets with two fluid passages between them.
U.S. Pat. No. 5,453,188 which issued on Sep. 26, 1995 to Florescu et al., is entitled Magnetic Apparatus for Preventing Deposit Formation in Flowing Fluids. This patent describes an apparatus and a method for minimizing the formation of deposits of paraffin, asphaltine and scale on the surface of tubing in an oil well by increasing the turbulence of various electrically-charged microscopic particles populating crude oil colloidal suspensions, using effects of the Lorentz force which acts upon the flowing fluid. A plurality of spaced-apart permanent magnet disc assemblies are disposed perpendicularly of a fluid flowing through the tubing. The disc assemblies are specially configured to provide a unique helicoidal trajectory of the various electrically-charged microscopic particles, subjecting those particles to a prolonged exposure to an intense magnetic flux. As the fluid flows through the central passageway, the charged particles exhibit turbulent, helicoidal flow through the concentrated magnetic lines of force. A problem with this arrangement is the severe flow restriction required in the fluid flow path.
Applicant""s Published Canadian Patent Application No. 2,240,016, which was filed on Jun. 8, 1998 is entitled An Apparatus For Magnetically Treating Flowing Fluids. This application discloses an apparatus for magnetically treating fluids removed from a hydrocarbon well. The apparatus includes a hydrocarbon section and a reactor section. The hydrocarbon section is designed to treat crude oil to inhibit the deposition of paraffins, asphaltines, and the like. The reactor section is designed to treat aqueous fluids to inhibit the deposition of scale, and the like. The magnets in the two sections are arranged in a linear, co-axial relationship. Radial focus magnets are provided in the reactor section to distort the magnetic field and provide radial exposure of the magnetic flux.
The devices described in the above prior patents and applications all teach magnets arranged in a radial relationship, except for the second embodiment described in U.S. Pat. No. 5,024,271 and Applicant""s Canadian Patent Application. The device described in U.S. Pat. No. 5,024,271 has a magnet circuit with a complicated structure. However, none of these patents teach effective treatment of fluids to prevent formation of deposits of barium sulfate on a production tubing in an oil well without unduly restricting production flow.
Consequently, there exists a need for a simple, linear arrangement of magnets that effectively treat well fluids to inhibit the formation of deposits of barium sulfate on the surfaces of a production tubing in an oil well, while having no significant impact on fluid flow through the production tubing.
It is therefore an object of the present invention to provide an apparatus for magnetically treating fluids produced from hydrocarbon wells to inhibit deposition of barium sulfate on tubulars used to produce the fluids from the wells.
Another object of the invention is to provide an apparatus and method for magnetically treating fluids in which magnets are arranged in a axial and radial relationship so that constriction of the fluid path is minimized.
The invention therefore provides an apparatus for treating fluids flowing through a conduit. The apparatus comprises a hydrocarbon section for treating hydrocarbon flowing through the conduit, and a reactor section for treating mineral-laden water that flows through the conduit. The reactor section includes four focus magnets that are arranged to treat the water so that even low-solubility minerals such as barium sulfate do not form scale deposits in the conduit.
The four focusing magnets are arranged in a linear distribution and are respectively supported in pockets affixed to a sidewall of the reactor section. A first of the four focusing magnets is on one side of the reactor section, while a next two of the four focusing magnets are spaced apart along an opposite side of the reactor section. The fourth focusing magnet is located upstream of the other three, and radially offset from the second and third focusing magnets. The degree of offset is preferably between 45xc2x0 and 67.5xc2x0 from the second and third focusing magnets.
Experimental testing of the tool has demonstrated that it is very effective in inhibiting the deposit of asphaltines, paraffins and mineral scales on the sidewalls of production tubings used to produce hydrocarbons from subterranean wells. Even low-solubility minerals such as barium sulfate are effectively inhibited from forming scale on the production tubing.
Consequently, the invention provides an apparatus that is easy and economical to install, and requires no maintenance. The apparatus can provide years of effective service and, unlike chemical scale inhibitors, does not require renewal.